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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>advance</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-iterator.html">iterator</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-iterator.html">&lt;iterator&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> InputIt, <span class="kw1">class</span> Distance <span class="sy1">&gt;</span><br />
<span class="kw4">void</span> advance<span class="br0">(</span> InputIt<span class="sy3">&amp;</span> it, Distance n <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx17">(C++17 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> InputIt, <span class="kw1">class</span> Distance <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">void</span> advance<span class="br0">(</span> InputIt<span class="sy3">&amp;</span> it, Distance n <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<p>&#22686;&#21152;&#32473;&#23450;&#30340;&#36845;&#20195;&#22120; <code>it</code> &#20197; <code>n</code> &#20010;&#20803;&#32032;&#30340;&#27493;&#38271;&#12290;</p>
<p>&#33509; <code>n</code> &#20026;&#36127;&#65292;&#21017;&#36845;&#20195;&#22120;&#33258;&#20943;&#12290;&#35813;&#24773;&#20917;&#19979;&#65292; <code>InputIt</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-BidirectionalIterator.html"><span style="font-style:italic">&#32769;&#24335;&#21452;&#21521;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyBidirectionalIterator)</span></a> &#30340;&#35201;&#27714;&#65292;&#21542;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
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<td>it</td>
<td>-</td>
<td>&#35201;&#21069;&#36827;&#30340;&#36845;&#20195;&#22120;</td>
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<td>n</td>
<td>-</td>
<td><code>it</code> &#35201;&#21069;&#36827;&#30340;&#20803;&#32032;&#25968;</td>
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<td colspan="3">&#31867;&#22411;&#35201;&#27714;</td>
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<code>InputIt</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">&#32769;&#24335;&#36755;&#20837;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyInputIterator)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#65288;&#26080;&#65289;</p>
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<p>&#32447;&#24615;&#12290;</p>
<p>&#28982;&#32780;&#65292;&#33509; <code>InputIt</code> &#39069;&#22806;&#28385;&#36275;<a href="cpp-named_req-RandomAccessIterator.html"><span style="font-style:italic">&#32769;&#24335;&#38543;&#26426;&#35775;&#38382;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyRandomAccessIterator)</span></a> &#30340;&#35201;&#27714;&#65292;&#21017;&#22797;&#26434;&#24230;&#26159;&#24120;&#25968;&#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#33509;&#25351;&#23450;&#30340;&#33258;&#22686;&#25110;&#33258;&#20943;&#24207;&#21015;&#35201;&#27714;&#19968;&#20010;&#19981;&#21487;&#33258;&#22686;&#36845;&#20195;&#22120;&#65288;&#20363;&#22914;&#23614;&#21518;&#36845;&#20195;&#22120;&#65289;&#33258;&#22686;&#65292;&#25110;&#19981;&#21487;&#33258;&#20943;&#36845;&#20195;&#22120;&#65288;&#20363;&#22914;&#39318;&#36845;&#20195;&#22120;&#25110;&#23396;&#31435;&#36845;&#20195;&#22120;&#65289;&#33258;&#20943;&#65292;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">&#21487;&#33021;&#30340;&#23454;&#29616;</span></h3>
<p>&#21442;&#38405; <a rel="nofollow" class="external text" href="https://github.com/gcc-mirror/gcc/blob/d9375e490072d1aae73a93949aa158fcd2a27018/libstdc%2B%2B-v3/include/bits/stl_iterator_base_funcs.h#L200">libstdc++</a> &#19982; <a rel="nofollow" class="external text" href="https://github.com/llvm-mirror/libcxx/blob/a12cb9d211019d99b5875b6d8034617cbc24c2cc/include/iterator#L582">libc++</a> &#20013;&#30340;&#23454;&#29616;&#12290;</p>
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<th>&#29256;&#26412;&#19968;</th>
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<div class="cpp source-cpp">
<pre class="de1"><span class="co1">// &#32463;&#30001;&#26631;&#31614;&#27966;&#21457;&#30340;&#23454;&#29616;&#65292;&#31227;&#38500; constexpr &#21518;&#21487;&#29992;&#20110; C++98</span>
<span class="kw1">namespace</span> detail <span class="br0">{</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> It<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++17 &#36215;&#35201;&#27714;</span>
<span class="kw4">void</span> do_advance<span class="br0">(</span>It<span class="sy3">&amp;</span> it, <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> n,
<a href="cpp-iterator-iterator_tags.html"><span class="kw652">std::<span class="me2">input_iterator_tag</span></span></a><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>n <span class="sy1">&gt;</span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">--</span>n<span class="sy4">;</span>
<span class="sy2">++</span>it<span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> It<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++17 &#36215;&#35201;&#27714;</span>
<span class="kw4">void</span> do_advance<span class="br0">(</span>It<span class="sy3">&amp;</span> it, <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> n,
<a href="cpp-iterator-iterator_tags.html"><span class="kw655">std::<span class="me2">bidirectional_iterator_tag</span></span></a><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>n <span class="sy1">&gt;</span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">--</span>n<span class="sy4">;</span>
<span class="sy2">++</span>it<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">while</span> <span class="br0">(</span>n <span class="sy1">&lt;</span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">++</span>n<span class="sy4">;</span>
<span class="sy2">--</span>it<span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> It<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++17 &#36215;&#35201;&#27714;</span>
<span class="kw4">void</span> do_advance<span class="br0">(</span>It<span class="sy3">&amp;</span> it, <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> n,
<a href="cpp-iterator-iterator_tags.html"><span class="kw656">std::<span class="me2">random_access_iterator_tag</span></span></a><span class="br0">)</span>
<span class="br0">{</span>
it <span class="sy2">+</span><span class="sy1">=</span> n<span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span> <span class="co1">// namespace detail</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> It, <span class="kw1">class</span> Distance<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++17 &#36215;</span>
<span class="kw4">void</span> advance<span class="br0">(</span>It<span class="sy3">&amp;</span> it, Distance n<span class="br0">)</span>
<span class="br0">{</span>
detail<span class="sy4">::</span><span class="me2">do_advance</span><span class="br0">(</span>it, <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span><span class="br0">(</span>n<span class="br0">)</span>,
<span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">iterator_category</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<th>&#29256;&#26412;&#20108;</th>
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<div class="cpp source-cpp">
<pre class="de1"><span class="co1">// &#32463;&#30001; constexpr if &#30340;&#23454;&#29616;&#65292;&#21487;&#29992;&#20110; C++17</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> It, <span class="kw1">class</span> Distance<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="kw4">void</span> advance<span class="br0">(</span>It<span class="sy3">&amp;</span> it, Distance n<span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">using</span> category <span class="sy1">=</span> <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">iterator_category</span><span class="sy4">;</span>
static_assert<span class="br0">(</span><a href="cpp-types-is_base_of.html"><span class="kw591">std::<span class="me2">is_base_of_v</span></span></a><span class="sy1">&lt;</span><a href="cpp-iterator-iterator_tags.html"><span class="kw652">std::<span class="me2">input_iterator_tag</span></span></a>, category<span class="sy1">&gt;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">auto</span> dist <span class="sy1">=</span> <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>It<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span><span class="br0">(</span>n<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="kw4">constexpr</span> <span class="br0">(</span><a href="cpp-types-is_base_of.html"><span class="kw591">std::<span class="me2">is_base_of_v</span></span></a><span class="sy1">&lt;</span><a href="cpp-iterator-iterator_tags.html"><span class="kw656">std::<span class="me2">random_access_iterator_tag</span></span></a>, category<span class="sy1">&gt;</span><span class="br0">)</span>
it <span class="sy2">+</span><span class="sy1">=</span> dist<span class="sy4">;</span>
<span class="kw1">else</span> <span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>dist <span class="sy1">&gt;</span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">--</span>dist<span class="sy4">;</span>
<span class="sy2">++</span>it<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">if</span> <span class="kw4">constexpr</span> <span class="br0">(</span><a href="cpp-types-is_base_of.html"><span class="kw591">std::<span class="me2">is_base_of_v</span></span></a><span class="sy1">&lt;</span><a href="cpp-iterator-iterator_tags.html"><span class="kw655">std::<span class="me2">bidirectional_iterator_tag</span></span></a>, category<span class="sy1">&gt;</span><span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>dist <span class="sy1">&lt;</span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">++</span>dist<span class="sy4">;</span>
<span class="sy2">--</span>it<span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="br0">}</span></pre></div>
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<p><br /></p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<div class="t-example-live-link"></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;iterator&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-container-vector.html"><span class="kw1268">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> v<span class="br0">{</span> <span class="nu0">3</span>, <span class="nu0">1</span>, <span class="nu0">4</span> <span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">auto</span> vi <span class="sy1">=</span> v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
std<span class="sy4">::</span><span class="me2">advance</span><span class="br0">(</span>vi, <span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="sy2">*</span>vi <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
<p>&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">4</pre></div>
</div>
</div>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
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<div><a href="cpp-iterator-next.html"><span class="t-lines"><span>next</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#20196;&#36845;&#20195;&#22120;&#33258;&#22686;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-iterator-distance.html"><span class="t-lines"><span>distance</span></span></a></div>
</div>
</td>
<td>&#36820;&#22238;&#20004;&#20010;&#36845;&#20195;&#22120;&#38388;&#30340;&#36317;&#31163;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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